Under a new federal program known as Secure Communities, a van belonging to the federal government regularly pulls up to Santa Cruz County Jail on Water Street to pick up illegal immigrants.

If you know who the immigrants are, you can find out where they were taken. But in a move that alarms some advocates, the federal Department of Immigration and Customs Enforcement won't share that information, and the local jail says it has no way of tracking that data.

"One of our biggest grievances about (Secure Communities) is the lack of transparency, both at the local level and the national level," said Tomas Alejo of the Immigrant Action Network.

Started in 2007 and pitched as a way to get dangerous offenders off the street, Secure Communities has met with controversy since its inception. Supporters say it helps enforce immigration laws, while critics say it amounts to a digital dragnet targeted at immigrant communities.

Last week, the Santa Cruz County Board of Supervisors added its voice to the debate, passing a resolution supporting a bill that aims to let counties opt out of the program. All California counties are now linked to the program, with Santa Cruz's jail having been hooked into the system in August.

Since then, more that 200 local county inmates have been transferred to ICE through the program. Eighty-six have been deported, with 11 of those having once been convicted of violent or serious felonies.

Concerning to rights groups is that 45 of the deportees were listed as "non-criminals," or 52 percent of those deported, much higher than the statewide average of 30 percent.

The 52 percent rate is among the highest in the state, and the highest in the Monterey Bay area, though Monterey County's rate follows closely at 48 percent.

So far, 35,000 people have been deported from California through the program. But without names, tracking the nearly 10,000 "non-criminals" deportees - what they were arrested for, what happened with their cases, where they are or what country they were returned to - is difficult.

ICE spokeswoman Lori Haley said the agency will only confirm the custody of specific detainees. But since immigration proceedings don't operate under the same rules as a court of law, ICE won't provide lists of those it is holding.

"They're administrative charges. They're not criminal," Haley said.

Even some critics of the Secure Communities acknowledge that ICE is not required to disclose broad lists of immigration holds, though efforts are under way to learn more details about the program despite those rules.

Santa Cruz County Chief Deputy Jeff Marsh, who oversees the county's jail system, said local jail databases are incapable of producing lists of which inmates were transferred to ICE.

But the program has resulted in changes. The old paperwork-intensive checks done by ICE were much slower, with detainees often being released before a hold was requested, Marsh said. Secure Communities now produces near-instantaneous hits.

But Marsh pointed out that the county has little to do with it: Jail officials don't request an immigration check.

"We don't ask the question," he said.

While the program was sold as away to catch habitual criminals, detainees listed as "non-criminal" don't have a criminal history. Haley said the listing has nothing to do with the charges for which they were arrested, raising the possibility that some were accused of serious, violent crimes.

But there are indications that those crimes weren't serious. The program has only been in place for eight months, and since serious crimes take longer to prosecute and defendants serve their sentences before being transferred to ICE custody, it is likely that many deported from Santa Cruz were not facing major charges, if any at all.

It is that group of deportees raising red flags for many.

Jon Rodney, a spokesman for the California Immigrant Policy Center, said he knows of one case in which an immigrant was deported after being stopped for running a red light. While the man was here illegally, such cases show that U.S. immigration policy needs to be fixed, Rodney said.

"We need to look at the big picture. We have an immigration system that most would agree is broken," Rodney said. "This is a dragnet that's impacting innocent people."

In Sacramento, Assemblyman Tom Ammiano, D-San Francisco, is pushing a bill to allow counties to opt out of the program and force ICE to report more information about who is being deported. New York's Benjamin N. Cardozo Law School is also pursuing a suit against ICE on behalf of immigrant groups that seeks similar information.

"It's clear the program is not operating the way it was said to be operating, and we have now crossed the line between law enforcement and immigration policy," said Quintin Mecke, an Ammiano spokesman.

Whether counties can opt out is another question. Ammiano's bill is set for a key April 26 hearing. Meanwhile, Ammiano met with Attorney General Kamala Harris earlier this week to discuss the program, and a spokesman said the attorney general is reviewing the program.

"The Department of Justice is having conversations with ICE, local law enforcement and the civil rights community to see what the parameters of this program are and how it is working," Harris spokesman Shum Preston said.